Water intake systems use various types of screens and barriers, and several systems have been developed to clean debris from the screens. For example, mechanical systems that use moving brushes have been used to clear screens of debris. In addition, removable forms of screens have been used in many locations to overcome cleaning issues.
In other implementations, screen cleaning systems can use bursts of air directed from a manifold to clean the screen of debris. For example, Johnson Screen's Hydroburst System is one system used for cleaning cylindrical intake screens. FIGS. 1A-1C show a water intake system 10 having a hydroburst system 20 according to the prior art. The hydroburst system 20 is used for implementations where the intake screen 30 may need regular cleaning when exposed to debris or when the screen 30 is difficult to access. When operated, the hydroburst system 20 flushes the debris away from the screen's surface by releasing a large volume of compressed air inside the screen 30 in a quick burst.
As shown in FIGS. 1A-1B, the hydroburst system 20 has a receiver tank 22 that stores compressed air and has a compressor 24 that charges the tank 22 with the compressed air. Distributor piping 28, valves 25, and the like couple the tank 22 to a header in the screen 30. Finally, a control panel 26 controls operation of the system 20.
The cylindrical screen intake 30 shown in FIG. 1C has a tee configuration with two screens 36 on opposing ends of a central body 34. A water outlet 32 connects from the central body 34 for connecting to other components of the water intake system 10. Air backwash headers 40 disposed in the screens 36 connect to an inlet pipe 42 that receives air from the hydroburst system 20. When an airburst communicated from the hydroburst system 20 reaches the headers 40, the resulting burst of air/water can clean the cylindrical screens 36 of debris.
Cleaning a screen with an airburst can be more difficult when the screen is flat. Such flat screens can be used for a number of applications, including water intake systems and fish diversion in dam and river systems to protect fish from hydroelectric turbines and pumps. Typically, the flat screens for these applications have a low-suction velocity to protect fish and other aquatic life. Yet, debris may still be able to collect on the screens.
One solution by Montgomery Watson Engineering for clearing debris from a flat screen is shown in FIGS. 2A-2B. A water intake module 50 buries in a bed of a waterway so that a portion of the module 50 sticks above the bed. The module 50 has a nose shield 54 at its upstream end. A supply pipe 56 runs from the module 50 to a water intake system, and a cleaning air pipe 60 and a buoyancy air pipe 65 run from the module 50 to components of an air supply system.
Internally, the module 50 contains flat fish screens 52, flow control slats 64, airburst cleaning pipes 62, floatation tanks 67, and a supply pipe connection 55. The flat screens 52, slats 64, and airburst pipes 62 situate at the top of the module 50, while the floatation tanks 67 situate at the bottom. The cleaning air pipe 60 of FIG. 2A connects to the airburst pipes 62 shown in FIG. 2B, and the buoyancy air pipe 65 of FIG. 2A connects to the flotation tanks 67 shown in FIG. 2B.
During use, water flows downward through the flat screens 52 and past the slats 64 into the module's collection chamber where the water can then travel to the supply pipe 56. The airburst pipes 62 are horizontally arranged PVC pipes located between the flat screens 52 and slats 64. These pipes 62 have small holes and distribute an airburst for cleaning the flat screens 52 when a burst of air is supplied. The slats 64 and pipes 62 have been used with horizontal modules 50 as shown in FIG. 2B, but they have also been used for vertical modules (not shown).
Another solution from Johnson Screens for clearing debris from a flat screen is shown in FIGS. 3A-3C. Here, a horizontal manifold 70 is used to clean a flat screen 52. The manifold 70 has distributor pipes 72 enclosed by troughs 74. A manifold frame 76 couples to the screen 52 or anchors by suitable stabilizing means downstream of the screen 52. Either way, the manifold frame 76 supports the deep troughs 74, which facilitate airflow from a backwash system 20 to the screen 52. As best shown in FIG. 3C, the troughs 74 have back panels 75, which can be solid as shown. Alternatively, the back panels 75 can be perforated or may not be present so water can flow through the deep troughs 74.
To provide the airflow, a conduit 73 couples from the backwash system 20 to each distributor pipe 72 enclosed in the troughs 74. Each distributor pipe 72 has a plurality of orifices (not shown) to direct a burst of air outwards toward the screen 52. When the backwash system 20 produces an airburst, for example, the air is directed from the pipes 72 and troughs 74 to the opposing screen 52 to clear debris. Water flow through the screen 52 and between the troughs 74 is shown by arrows.
Although the manifold 70 of FIGS. 3A-3C and other prior art systems may be effective, constructing such a trough-type manifold can be complicated and cost prohibitive for some implementations. Therefore, it would be useful for operators to be able to clean flat type screens effectively with an airburst system. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.